1. Field of the Invention
The present invention relates generally to a system for providing stable tape-travel in recording and/or reproducing apparatus, such as video tape recorders (VTR). More specifically, the invention relates to a system which can prevent the occurrence of slack in tape which travels in a recording and/or reproducing apparatus when the tape traveling direction is switched between forward and reverse.
2. Description of the Prior Art
In recent years, some recording and/or reproducing apparatus, such as video tape recorders, use a common motor which drives a capstan axle as well as two reel tables in order to make the apparatus more compact.
In such recording and/or reproducing apparatus, time motor causes time capstan axle to rotate clockwise or counterclockwise for causing magnetic tape to travel along a tape traveling path in a forward or reverse direction. The magnetic tape is urged toward the capstan axle by means of a pinch roller so as to travel depending upon the rotation of the capstan axle. The motor also causes two reel tables, i.e. a supply reel table and a take-up reel table to selectively rotate clockwise or counterclockwise via a pendulum gear which is movable between time supply and take-up reel tables. The pendulum gear is engageable with respective reel tables via idler gears. With this construction, for example, in order to cause the magnetic tape to travel in the forward direction, the capstan motor rotates counterclockwise, so that the magnetic tape is fed toward the take-up reel table depending upon the rotation of the capstan axle. At this time, the pendulum gear engages the take-up reel table via an idler gear so that the take-up reel table rotates clockwise for winding magnetic tape thereon. On the other hand, in order to cause the magnetic tape to travel in the rearward direction, the capstan motor rotates clockwise, so that the magnetic tape is fed toward the supply reel table depending upon the rotation of the capstan axle. At this time, the pendulum gear engages the supply reel table via its idler gear so that the supply reel table rotates counterclockwise for winding the magnetic tape thereon.
On the other hand, in recent years, some video tape recorders have a so-called JOG/SHUTTLE function which may suitably perform reproduction in forward or reverse directions at a slow-speed, a usual-speed or a high-speed. In such video tape recorders, for example, when the operation mode is switched from a forward reproduction mode in which the magnetic tape travels in the forward direction while the reproduction of picture signals is performed, to a reverse reproduction mode in which the magnetic tape travels in the reverse direction while the reproduction of picture signals is performed, there is a disadvantage in that tape drop-out, jitter, picture noise and so forth are produced at the switching time.
That is, when the operation mode is switched from the forward reproduction mode to the reverse reproduction mode, the supply and take-up reel tables do not rotate to take up the magnetic tape thereon while the pendulum gear is moving between the reel tables, although the capstan axle continues to rotate, feeding magnetic tape toward the supply reel table. As a result, slack in the tape traveling path is produced, so that the magnetic tape can not suitably come into proper contact with a rotary head drum; thus, tape drop-out, jitter, picture noise and so forth are caused.
In order to prevent the aforementioned disadvantage, the tape may be prevented from being fed by releasing the pinch roller from contact with the capstan axle while the pendulum gear is moving between the supply and take-up reel tables. However, when the tape pinch roller is released from tight contact against the capstan axle, the position of the magnetic tape tends to shift relative to the rotary head drum. In addition, switching operations between forward and reverse reproduction modes cannot be rapidly performed. Therefore, the above solution cannot be used for video tape recorders having a JOG/SHUTTLE function.
In addition, in recent years, some video tape recorders have a tape tension regulating mechanism which applies a constant tension to the magnetic tape for maintaining suitable contact conditions between the magnetic tape and the rotary head drum. Such conventional tension regulating mechanisms are designed to apply tension to the magnetic tape when the operation mode is the forward reproduction mode, and to release tension from being applied to the magnetic tape when the operation mode is switched from the forward reproduction mode to the reverse reproduction mode. As a result, when the operation mode is switched from forward to reverse, a disadvantage occurs in that slack in the tape traveling path is produced, so that the position of the magnetic tape may shift from a suitable position on the rotary head drum, causing occurrence of tape drop-out, jitter, picture noise and so forth.